This invention relates to jet engine cowling structure and more particularly relates to a system for attaching the inlet cowl of an engine system to the engine containment case.
Typically, the inlet cowl associated with a jet engine is a separate piece that must be attached to the engine containment case. The prior art system used to attach the inlet cowl to the engine containment case has been a heavy, forged ring attached by bolts to a flange formed on the forward end of the engine containment case. Typically, the interior surface of the inlet cowl is lined with an acoustic treatment material, such as a honeycomb core covered by a perforated skin, to control the noise produced by the engine. The prior art inlet cowl attachment system utilizes a doubler plate fastened to the forged ring to add strength to the attachment area. The double plate is solid and negates the function of the perforated skin of the acoustic treatment material in the area covered by the doubler plate. The effective area of the acoustic treatment panel is reduced by the size of the doubler; therefore, in order to achieve the required effective area of acoustically treated inlet surface, it is necessary to make the inlet cowl longer in an amount equal to the width of the doubler. The use of a heavy, forged ring plus the doubler plate and the need to lengthen the inlet cowl to compensate for the presence of the doubler plate all tend to add a significant amount of weight to the aircraft upon which the engine is mounted.